The roles of Non-Governmenta Organization (NGOs) in Thailand are significant to environmental protection. The government's acceptance thereof is evidenced by the enactment of Section 7 of the Enhancement and Conservation of National Environmental Quality Act, B.E. 2535 which provides that all NGOs engaging in environmental protection shall be juristic persons under Thai or foreign laws and shall have to be registered as NGOs engaging in the protection and conservation of natural resources and environment with the Ministry of Science, Technology and Environment. Such requirements are measures for the overseeing of the operation of the environmental NGOs. The law also provides incentives and promotion for NGO roles in environmental protection by rendering assistance when they run into problems. Financial support is also given to assist operation from Environmental Fund in accordance with Section 8. Many of the NGOs do not have sufficient potential required by law to register as environmental NGOs ; therefore,only a few are registered NGOs. Environmental protection activities of the environmental NGOs are carried out directly and indirectly. NGOs play their direct roles in management of environment, dissemination of information, and exercise of environmental rights. Indirectly, their roles are also played through the National Environment Boad in which 4 of their representatives are members among the total number of 23 members. However, NGOs are not entitled to nominate their representatives for submission to the Council of Ministers for approval for their appointment as members of the Board. Some NGOs do not know who their representatives are, and this hinders their indirect activities. Inaddition, NGOs also play another role in exercising their rights and performing their duty as provided by law. Their rights include the right to obtain information from government agencies, the right to claim damages or compensation from the State, state enterprise, or any individual whose project causes damage, as well as theright to lodge conplaints against environment violators. As for their duty, they are required by law to protect the environment and to co-operate with officials in carrying out their environmental protection duty. This study recommends that the State amend the law concerning the qualification of the NGO required for the registration as an environemtal NGO, and increase the ratio of the expert menbers from NGOs on the National Environment Board. It is also recommended that a Ministerial Regulation be issued presecibing details and procedures for the nomination of the NGO representatives on the National Environment Board. It is also recommended that the NGOs omprove their pattern of activities and create a network of environmental NGOs, as well as invite academicians from universities to join them more participation in order to step up their activities thus strengthening the NGOs' academic potential.